Daikin EDLA14D3V3 COP is now below 1
Our Daikin EDLA14D3V3 heat pump was installed a year ago, at the start of a renovation, and the house has been maintained since at 14 or 15 deg. C to keep it aired and the DHW is off, apart from a weekly disinfection cycle.
The installers left the pump running with a fixed radiator temp of 35 deg. C. I became concerned about the performance when the heat exchangers became permanently heavily iced in cold weather and the compressor seemed to be working excessively hard. Analysing the data, I found it was achieving a COP of only 1.9.
I asked the installers to review the settings and they switched to a weather dependant slope temperature, which makes sense. Initially, the house warmed to 17.5 deg. C, so I reduced the offset over the next couple of days until it returned to 14 deg. C. The radiator temperate is now between 20 and 24 deg. C. The weather since the change was made has been milder than before, and the compressor has only been on intermittently.
The COP is now less than 1.0 !!!
Can anyone shed any light on the above, please? The rise in energy consumption and terrible COP seem counterintuitive.
Hi @pipcart,
Your ASHP is barely ticking over and is almost certainly starting and stopping a lot. It has a baseline power consumption just to keep it running and it'll be delivering very little energy to keep the rads at 24 degrees. In addition, the Legionnaire's cycle will skew the numbers more than when running normally. I'd expect power consumption and COP to be low in these circumstances.
In addition, the internal estimates of energy consumption and delivery are often very inaccurate at times of low use.
I wouldn't worry about it unless consumption seems excessive. Wait until you're using it in anger to see how it's performing. It shouldn't spend long periods iced up though. It will ice up in cold weather but should spend most of its time running normally. Did the installers have anything to say about that?
Thanks Kev M, that's reassuring, although the COP curves I have found online show increasingly high efficiency as radiator temperatures drop, even into the low 20s C. Also, the temperature curve drops to 20 in warmer weather, so I'm not clear how the pump will perform then.
I think you are right that we will not really get a clear picture until we are living in the house.
The installers were concerned about the icing, which improved once weather dependency was switched on.
At present, the cost of running the unit is outweighing the benefits. I could reduce cost by returning to a fixed temperature, but that seems a bit daft.
When the ASHP COP is tested it's not done in a real house but on some sort of test rig. On the test rig, even though the flow is only 20 degrees, the ASHP will be running continuously at its nominal capacity, which means it will be outputting 12kW or so. That won't ever happen in a real house; like I said yours is switching on and off and outputting a fraction of that. It's like mpg figures; comparing stop start city driving with driving along a long, flat, smooth road at the same average speed.
Running at a higher flow at very low demands isn't such a daft idea. This can lead to less cycling (ons and offs) and may be a better way to run your system where the heat demand is very low. I don't know how your Daikin is set up but can you run on weather compensation and use a thermostats that can stop the ASHP when it gets to a certain room temp?
Although it goes against all normal ASHP advice, in your situation you might even be better off heating your house to a higher temperature for part of the day rather than keeping it very low all the time.
@Kev M
Thanks for the further advice. I'm going to turn the offset temp (flow) up and use the room thermostat to limit the room temperature, which is what I think you are suggesting.
I'm now getting 1/2 hourly data from our smart meter and temperature lovers inside and outside the house, so I should be able to evaluate the effect of the change.
I'll post the results here.
Using our house as an example, with a system that is by no means as efficient as it should be, our COP for the past fortnight has been 2.5 (running on weather compensation) with ambient temperatures of 0-8C, so I would have expected your system to certainly be over 1 even with the low target temperatures. Frequent stop/starts as Kev has pointed might be the issue here.
What is your electricity consumption like?
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk
-
Viessmann Vitocal 250-A in the UK
3 months ago
-
Slash Your Heat Pump Bills Overnight
5 months ago
-
LG Therma V. Software upgrades, AI (weather compensation), SCOP
6 months ago
-
Does your heat pump calculate and provide you with a COP figure?
7 months ago
-
Vaillant Arotherm yeild and COP readings
8 months ago
- 25 Forums
- 1,513 Topics
- 31.8 K Posts
- 35 Online
- 1,283 Members
Join Us!
Latest Posts
-
RE: Additional Battery v Wind Turbine v Ripple
I should add, being an investment, the value of your in...
By Old_Scientist , 4 hours ago
-
RE: Ecodan - flow rates, sensors, settings
Achieving an accurate flow measurement is probably the ...
By Derek M , 8 hours ago
-
RE: Ecodan ASHP - How to optimise my set up?
Again, thank you for another thorough post, @derek-m - ...
By rhh2348 , 10 hours ago
-
RE: Delivering a smart and secure electricity system: government consultation
@Transparent.Now that I am represented by a new MP I th...
By IanMK13 , 12 hours ago
-
RE: Vaillant aroTHERM plus not level or flat - what base is best under an external unit?
Similar thread here
By Johnmo , 13 hours ago
-
RE: VDI 2035 heating water specification
Been looking and it seems a good little project. Ever...
By Johnmo , 2 days ago
-
RE: Do I accept an ASHP and Solar Panel retrofit under the HUG 2 scheme?
Will do. I'm currently waiting for another survey / vis...
By dssr , 2 days ago
-
The company that did the borehole were expecting us to ...
By Johnmo , 2 days ago
-
-
RE: The Misquote That Ruined the Heating Industry
@abernyte manufacturer training is pretty average. They...
By Mars , 2 days ago
-
-
RE: ECO4 Scheme and EPC ratings
@mellow Thanks. Given there is a scheme requirement to ...
By Old_Scientist , 3 days ago
-
RE: Do I just go with the lowest quote for my heat pump?
@jancold To me its a no-brainer then, a max 40C flow te...
By bontwoody , 3 days ago
-
-
RE: Heat Pump Books Beginners – Bodge Buster & From Zero To Heat Pump Hero
@editor Presumably he had some good weather Compensatio...
By Toodles , 4 days ago
-
RE: New Vaillant 7kW aroTherm ASHP or oil boiler dilemma/decision??
Storage capacity really is dependent on storage tempera...
By Johnmo , 4 days ago
-
RE: HP Cycling, Expected or Undesirable
Just a little update. I ordered a longer shielded twin ...
By bontwoody , 4 days ago
-
RE: Domestic hot water timer doing crazy things on my Grant Aerona3 10kW air source heat pump
Thanks @allyfish for the pics and info. Spoke to the in...
By Mellow , 4 days ago
-
RE: Aira Heat Pump: Stylish Scandinavian Heating
It's been a busy day for calls and emails from Aira. I ...
By MikeH , 4 days ago
-
RE: Heat Pump Servicing & Maintenance – Good Value or Rip-Off?
Hmm. A bit of a nuanced answer, methinks. As I've alr...
By Majordennisbloodnok , 4 days ago
Latest Topics
-
Ecodan - flow rates, sensors, settings
By rhh2348 11 hours ago
-
Replacing mains water with well water
By Johnmo 2 days ago
-
Additional Battery v Wind Turbine v Ripple
By bontwoody 2 days ago
-
By jamespipe 3 days ago
-
VDI 2035 heating water specification
By Johnmo 3 days ago
-
Do I just go with the lowest quote for my heat pump?
By Jancold 5 days ago
-
The Misquote That Ruined the Heating Industry
By Alec Morrow 5 days ago
-
Battery Storage Wiring Gauge Question
By Puff 6 days ago
Members Online
No online members at the moment